On The Real Housewives of Beverly Hills, Kim Richards sometimes seems like the saddest of the bunch. She fights with her sister Kyle, has had trouble finding a new home and admits she feels awkward and lonely since her divorce.

But the reality-TV drama is nothing compared the pain of her past.

Nineteen years ago, Richards was engaged to commodities salesman John J. Collett, then 29, of Agoura Hills, Calif. After following her career in films like Disney's Escape from Witch Mountain, he met his movie star crush and they dated for several months before they began to discuss their dream wedding.

"She loved him and he loved her and it was like a fairy tale," his sister Nina Stormo, 35, tells PEOPLE. "They seemed really happy."

Murder-for-Hire

But in October of 1991, Collett was gunned down by a hit man outside a San Fernando Valley deli in what may have been a business scheme gone horribly wrong. Richards had to identify the body.

"It just tore her apart emotionally and she was not in good shape for a long time," Collett's mother Jan Collett tells PEOPLE. "She really loved John. They were a good match."

Marva DeCarlo Johnson, 31, was sentenced in June of 1993 to 30-years-to-life after he was found guilty of murder. Prosecutors presented evidence that it was a paid hit, but did not present evidence of who bankrolled it or why.

Before his death, Collett had worked for a commodities firm that allegedly defrauded investors for millions. He became one of six defendants in a civil suit filed by California regulators.

A Lot of Pain

Prosecutors at DeCarlo's trial denied any connection between the lawsuit and the murder, but did not get into details about the true motive behind the hit.

Jan Collett, who has collected information over the years and is planning a book project, believes that her son was a victim of a separate criminal scheme. In this other conspiracy, she says, a rich businessman convinced wealthy acquaintances to invest serious cash – $250,000 in Collett's case – and instead of repaying the investors, he hired a hit man to kill them off.

Either way, Collett says, Richards has never recovered.

"Kim was always carrying around a lot of pain, subsequent to my son's death," Collett says. "I really cared for Kim. I thought she was a really good person with a good heart."